The field of the invention is in the nondestructive testing art and more particularly in the art of nondestructive testing of fiberglass-aluminum honeycomb structures.
There are many well known machines for nondestructive testing of structures. Some of the better known are atomic particle radiation systems, X-rays devices, sonic devices, permeability measuring devices, and various resistive and capacitive devices. Many of the prior art devices are laboratory instruments, few are portable enough to permit testing of structures in the field.
In many instances it is highly desirable to expediently test or examine assembled fiberglass-aluminum honeycomb structures such as helicopter blades and other similar aircraft structures for the presence of entrapped water, moisture, foreign fluids, and vapors which could cause a future failure of the structure. The present invention is particularly well suited for the foregoing. The best known prior art of interest in the background of the present invention is contained in the following patents. U.S. Pat. No. 2,831,123 to patentee Webster J. Daly; U.S. Pat. No., 3,237,068 to patentee Milton M. Sowiak; U.S. Pat. No. 3,351,760 to patentee R. L. Brown; and U.S. Pat. No. 3,809,974 to patentees R. A. Grange et al.